What is a reprogrammable microcomputer?

A microcomputer is a small, relatively inexpensive computer having a central processing unit (CPU) made out of a microprocessor.[2] The computer also includes memory and input/output (I/O) circuitry together mounted on a printed circuit board (PCB).[3] Microcomputers became popular in the 1970s and 1980s with the advent of increasingly powerful microprocessors. The predecessors to these computers, mainframes and minicomputers, were comparatively much larger and more expensive (though indeed present-day mainframes such as the IBM System z machines use one or more custom microprocessors as their CPUs).